llflllllllllllllllllll‘L 1""‘g‘aagr‘l Michigan Mate w—u—v v w— This is to certify that the thesis entitled THE EFFECT OF TILLAGE METHOD AND FERTILIZATION ON THE YIELD AND ELEMENTAL COMPOSITION OF CORN AND SOYBEANS presented by William H. Darlington has been accepted towards fulfillment of the requirements for M. S . degree in SQiLSCJ-Bnfifi' Major professor Date June 8. 1983 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES n \r RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. L « '_’ ' [WOS'esz-E. 5}; g; «mar. W V 0 160 5— 597/ ' / ’ I I /'~%’ THE EFFECT OF TILLAGE METHOD AND FERTILIZATION ON THE YIELD AND ELEMENTAL COMPOSITION OF CORN AND SOYBEANS By William Henry Darlington A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crap and Soil Science 1983 ABSTRACT THE EFFECT OF TILLAGE METHOD AND FERTILIZATION ON THE YIELD AND ELEMENTAL COMPOSITION OF CORN AND SOYBEANS by William H. Darlington Corn (Zea Mays L.) and soybeans (Glycine Max. L. Merr) were grown under no-tillage and conventional tillage systems. The effects of two K rates and banded versus broadcast P on yields and nutrient composition of plant and grain samples were determined. TWO N rates in the corn study and two soybean varieties were also evaluated. Corn grain yields were higher in no-till than conventional plots. Soybean yields averaged 4,300 kg/ha2 in both tillage systems although final plant population was 17% lower in no-till. Early N and P uptake was greater in no-till corn than in conventionally tilled corn. Lower N content was observed in no-till ear leaf samples at silking and stover and grain at harvest, particularly at the low N rate. High N increased corn grain and stover yields. Surface residue in no-till plots had little effect on soil temperatures, soil moisture and corn root distribution. Tillage decreased soil bulk density and increased aeration. ACKNOWLEDGEMENTS $hmmre gratitude and appreciation is expressed to Dr. M. L. Vitosh for his encouragement, support and constructive criticism during each phase of this project. Gratitude is expressed to Dr. A. E. Erickson for his suggestions and support during this study. I sincerely thank Dr. L. S. Robertson and Dr. D. Krauskon for their assistance on my guidance committee. 1R3Im11as Hyde and Jon Dahl, for encouragement and invaluable assistance I am deeply grateful. Thanks are due to Calvin Bricker and Rosie Cabrera for their instruction and assistance in the laboratory and to Mark Collins, Gregg Vanek, Bob Every and many others for their assistance in the field. Funding was provided by Sohio and the Michigan Soybean Committee. 11 TABLE OF CONTENTS LIST OF TABLES.................................................... LIST OF FIGURES................................................... INTRODUCTION...................................................... LITERATURE REVIEW................................................. Soil Properties Affected by Tillage and Crap Residue........... $011 MOiStureoooo00000000000000.0000.ooooooooooooooooooooeooo Bulk Density and Soil Aeration............................... Soil Aggregation............................................. Soil Temperature............................................. Effect of Residues on Yields................................. Nitrogen Transformations as Affected by Tillage and Residue.... Fertilizer Use Efficiency as Affected by Tillage and Surface Residue........................................................ N-Rate Studies............................................... N-Source Studies............................................. N-Placement Studies.......................................... Phosphorus Studies........................................... Potassium Studies............................................ Calcium and Magnesium Studies................................ Soil Acidity and Liming Studies.............................. Micronutrient Studies........................................ EXPERIMENTAL METHODS.............................................. Experimental Design and Management Practices for Corn.......... Experimental Design and Management Practices for Soybeans...... Growth and Yield............................................... Chemical Analysis.............................................. $011....OOOOOOOIOOCOOOOOOOOOOOOOOOOOOOOOOOOCOOOOOOOOOOOO...O. Plant Nutrient compOSitionoooooooooooosoooooso.00000000000000 iii Page vii \D Gl\lc\£‘£> 10 l3 13 14 16 17 20 21 22 23 24 24 26 28 28 28 29 iv Soil Physical Properties....................................... Soil Temperature and Moisture................................ Percent Residue Cover........................................ Bulk Density and Air-Filled Porosity......................... Root Distribution............................................ StatiStical Analy318000000000000000000000000000000000.ooooooooo RESULTS AND DISCUSSION.oooooooooooooooooooooooooooooooooeooooooooo Field Conditions and 8011 Physical PrOperties as Affected by Tillage........................................................ Field Conditions at Planting................................. Soil Temperature............................................. 8011 MOiStureooooooooooo0.0000000000000000...0000000000000... BUlk DenSity and 8011 Aerationooooooooo00000000000000.0000... YiEldSooooooococo...ocoococooooooooooooooooooooooooo000000.000. cornooooooooooooooooooooeoooooooooo00000000000000.0000...one. SOYbeanOOOOOOOOOOOOO00.....0...O...0.000000000000000000000000 Plant ADBlYSiSooooooooooooooooooooooooooooooooooooooooooooooooo Corn........oo........................o...................... SOYbeanooooooooooooooooooooooocoooooooooooooooooooooooooooooo ROOt DEUSitYoooooooooooooooo00000000000oooooooooooooooooooooooo Summary and CODCIUSionSooo0000000000000oooooooooooooooooooooooo Recommendations........o.....o............o.................... APPENDIX .00...OOOOOOOOOOOOOOOOOOO00....OOOOOOOOOOOOOOO0.0.00.0... BIBLIOGRAPHY.OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO...OOOOOOOOOOOOOOOOOOOO 32 32 32 32 33 34 35 35 35 37 37 49 49 49 52 56 56 65 68 71 73 75 83 Table 10 11 12 13 LIST OF TABLES 8011 teSt levels for the corn tillage stUdYOOOOOOOOOOOOO... Soil test levels for the soybean tillage study............. Effect of tillage on germination, final corn population and percentage of barren stalks................................ Soybean plant population as affected by tillage and variety Corn grain yield as affected by tillage method, nitrogen and potassium rate and phosphorus placement.................... Corn grain moisture at harvest (October 18) as affected by tillage methOd and nitrogen rate...oooooooooooooooooooooooo Corn stover yield as affected by tillage method, nitrogen and potassium rate and phosphorus placement................ Soybean yield as affected by tillage method, variety, phosphorus placement and potassium fertilization........... Elemental composition of whole plants (early whorl stage) as affected by tillage method, nitrogen and potassium fertilization and phosphorus placementoooooooooeoo000000000 Elemental composition of corn ear leaf (early silking) as affected by tillage method, nitrogen and potassium fertilization and phosphorus placementooooooeoooooooooooooo Elemental composition of corn grain as affected by tillage method, nitrogen and potassium fertilization and phosphorus PlacemntOIOOOOOOO0.00000000000000000COOOOOOOOOOOOOOOOOOOOO Elemental composition of corn stover as affected by tillage method, nitrogen and potassium fertilization and phosphorus placementooooooooooooooooooooooooooooooocoo...cocoo-ooooooo Effect of tillage and nitrogen fertilizer on the elemental comp081tion Of corn grain (interaction BffECt3)ooooooooeooo v t Page 30 3O 36 36 51 53 54 55 57 58 59 6O 61 14 15 16 17 18 1a 2a Ba 43 5a 6a 7a 8a vi Effect of nitrogen and potassium fertilization on the elemental composition of corn grain (interaction effects).. Effect of tillage and potassium fertilization on the elemental composition of corn stover (interaction effect).. Elemental composition of soybean leaf (early bloom) as affected by tillage method, variety, phosphorus placement and pOtaSSium fertilizationoooooooocan...0.0000000000000000 Elemental composition of soybean grain as affected by tillage method, variety, phosphorus placement and potassium fertilization.00.000000000000000.0000000000000.000000000000 Corn root length density as affected by tillage, depth and diStance from IOWooeoooo000000000sooooooooooooooooooooooooo Corn tillage StUdy treatmentSoooo00000000000000000000000... Elemental composition of corn plants (early whorl) as affected by tillage method, nitrogen and potassium fertilization and phosphorus placement.coo-0000000000000... Elemental composition of corn ear leaf as affected by tillage method, nitrogen and potassium fertilization and phosphorus placement...000.000.000.000...oooooooooooooooooo Elemental composition of corn grain as affected by tillage method, nitrogen and potassium fertilization and phosphorus placement.ooooooooooooooooooooooo000000000.0000000000000000 Elemental composition of corn stover as affected by tillage method, nitrogen and potassium fertilization and phosphorus placement.coco-coco...00000000000000.0000.0.000000000000000 SOYbean tillage BtUdy treatmentSooooo00000000000000.0000... Elemental composition of soybean plants (early bloom) as affected by tillage method, variety, phosphorus placement and p0tassium fertilizationoooooooococo00000000000000.0000. Elemental composition of soybean seed as affected by tillage method, variety, phosphorus placement and potassium fertilizationoooooooocoo-coo...00000000000000.0000000000000 61 62 66 67 7O 75 76 77 78 79 8O 81 82 Figure 10 11 12 LIST OF FIGURES Corn study tensiometer readings at 30 cm as affected by and tillage.OOOOOOOOCOOOIOOOOOOOO0.0...OOOOCOOOOOOOOOOOOOO Soybean study tensiometer readings at 30 cm as affected by time and tillageoooooooo00000000000000.00000000000000.0000 Volumetric water content of soil (g/cm3) at 15 cm depth as affeCted by tillage; corn StUdYooooooooeooooooooooooooo Volumetric water content of soil (g/cm3) at 30 cm depth as affeCted by tillage; corn StUdYoo00000000000000.0000... Volumetric water content of soil (g/cm3) at 46 cm depth as affECted by tillage; corn StUdYQOoooooooooooooooooeoooo Volumetric water content of soil (g/cm3) at 15 cm depth as affeCted by tillage; SOYbean StUdYOoooooeooooo000000000 Volumetric water content of soil (g/cm3) at 30 cm depth as affECted by tillage; BOYbean StUdyoococo-000.000.0000.. Volumetric water content of soil (g/cm3) at 46 cm depth as affeCted by tillage; BOYbean St“dYo-ooo0000000000000... Distribution of soil water (g/cm3) with respect to depth as affeCted by tillage; corn BtUdYQOoooooooooooooooooooooo Distribution of soil water (g/cm3) with respect to depth as affected by tillage; soybean study..................... Tillage effects on aeration porosity of surface soil (0-8 cm) in corn tillage BtUdYoooooo00000000000000.0000... Influence of tillage and depth on corn root length per unit 8011 VOlumeoo0.000000000000000000000000000000.0000... vii Page 38 39 41 42 43 44 45 46 47 48 50 69 INTRODUCTION For more than 100 years, U.S. agriculture has relied upon the moldboard plow, disk and harrow to prepare soil to produce crops (70). Intensive cultivation was needed to control weeds. In the late 1940's selective herbicides were developed; therefore, it became feasible to grow many crops with less tillage or even without tilling the soil. No-till is a crop production system whereby a crop is planted directly into a seedbed not tilled since harvest of the previous crop (2). Coulters or disk Openers are often used on the planter to allow placement and coverage of the seed and fertilizer with soil. Weeds are controlled by chemical herbicides, and 3011 amendments, such as lime and fertilizer, are applied to the soil surface. The land area used for row craps and forage crops grown with the no-till system is increasing rapidly. In 1974, the U.S. Department of Agriculture (25) estimated that the acreage of no-till cropland in the United States was 2.2 million hectares. In 1981, an estimated 2.9 million hectares of crepe were grown with this system (3). Some authorities predict that 62 million hectares or 45 percent of the total U.S. crapland will be under the no-till system by 2000 (25). In Michigan, 45,507 hectares of corn (Zea mays L.) and 5,714 hectares of soybeans (Glycine max L. Merr.) were grown in 1982 using no-till accounting for 3.5 and 1.5 percent of the total acreage of these craps, respectively (4,25). The major advantages of the no-till cropping system are (1) soil 1 DJ erosion caused by wind and water is reduced, (ii) fuel and labor requirements are reduced (73,90), (iii) planting operations can be more timely, particularly in regions were climate allows for double-crapping (19,36,76), and (iv) soil water is conserved because of reduced evaporation and greater infiltration. There are also several potential problems associated with the no-tillage system (1) heavy residues often cause inadequate or non-uniform stands, (ii) the populations of weeds, disease-producing organisms and rodents may be higher than conventional tillage systems (42,55,56,72,92), (iii) soil temperatures are lower at planting which may delay planting or germination, and (iv) the availability of applied nutrients may be reduced. Special management is required to minimize these problems. The objectives of this study were (1) to define management practices needed to grow high yields of corn and soybeans with the no-tillage and conventional tillage systems, (2) to evaluate the effects of two tillage system and several fertility treatments on the yield and elemental composition of corn and soybeans, and (3) to determine the differences in physical and chemical properties of the soil as affected by two tillage systems. LITERATURE REVIEW Tillage Systems No-till soilsidiffer physically, biologically and chemically from conventionally tilled soils. The differences between nO-till and coventionally tilled soils can significantily affect yield, nutrient uptake and fertilizer efficiency. Researchers have tried to identify soil properties affecting yield, nutrient uptake and fertilizer efficiency under no-till systems and to develop management practices to» maximize these parameters. Much of the current literature dealing with tillage contains terminology that is inconsistent and incomplete. The following tillage systems terms, defined by the Soil Science Society of America (2), will be used in this report. conventional tillage-The combined primary and secondary tillage Operations normally performed in preparing a seedbed for a given geographical area. minimum tillage-The minimum soil manipulation necessary for crop production or meeting tillage requirements under the existing soil and climatic conditions. no-tillage-A crOp production system whereby a crop is planted directly into a seedbed not tilled since harvest of the previous crop. reduced tillage-A tillage sequence in which the primary Operation is performed in conjunction with planting procedures in order to reduce or eliminate secondary tillage operations. Soil Properties Affected by Tillage and Crop Residue The soil physical properties of no-till soils are often markedly different than conventionally tilled soils. Soil moisture, soil temperature, bulk density, porosity and soil structure are affected by tillage practices and residue management. The magnitude Of the differences in soil physical properties and the effects of these differences on crop growth and yield depend on the soil type, climatic conditions, the type and degree of soil manipulation by tillage and the type and amount of residue left on the soil surface. Soil Moisture The quantity and distribution Of water in the soil profile is affected by tillage practices and residue management. No-till fields generally have more available water in the surface 30 cm than tilled fields (13,14,22,30,35,39,47,51,87,93,99). The greatest difference occurs in the 0 to 8 cm depth, with no-till soils averaging 15 to 30 percent more water. Below a depth of 60 cm, tillage has little influence on soil moisture. The soil moisture distribution with depth in conventionally tilled soils is normally characterized by the lowest soil moisture values at the surface and increasing moisture with depth. No-till soils have high moisture values near the surface decreasing with depth until a high clay content region is reached (13). Moisture retention values are often higher in no-till soils (47). Little data is available on the moisture characteristics Of nO-till soils under irrigation. The surface residue associated with no-till systems promotes moisture conservation. Surface residue in nO-till fields acts as an insulator to reduce moisture loss by direct evaporation during the early growing period (l3,l4,35,39,87,93). Infiltration is greater in no-till soils because of the surface mulch (l3,l4,30,47,93). The mulch dissipates the energy of the raindrops and decreases dispersion and surface sealing. The presence of undisturbed but decaying plant roots may form root channels that serve as avenues for water infiltration into the soil (13). In some studies greater earthworm activity has also led to high infiltration rates in no-till plots (31,47). Increased infiltration reduces surface runoff from no-till soils. Moisture retention is increased by changes in organic matter content and differences in the structure and texture of the surface horizon. NO general statement can be made about the effect of soil moisture characteristics Of nO-till soils on corn growth and yield, since growth and yield responses depend on soil type and climatic conditions. On soils with low water holding capacities increased yields from no-till compared with plowing have been reported in Virginia, Kentucky and southern Illinois (49). On these soils, decreased evaporation under nO-till and the greater ability of the soil to store moisture resulted in a moisture reserve in the nO-till plots. This moisture reserve can carry the crap through periods of short-term drought without severe moisture stresses develOping in the plants. In Ohio and Indiana (49), however, no-till corn was the first to show water stress. In Ohio, the greater wilting in no-till plots was attributed to less available water and in Indiana to either a reduction in root growth or less soil moisture because of reduced infiltration. In Ohio (91), corn yields were increased by no-till on well drained sandy soils, but decreased by 5 to 15 percent on poorly drained soils. Experiences in Minnesota and on poorly drained soils in northern Illinois (49) indicate yields may be reduced by no-till. On poorly drained soils, wet conditions at planting may lead to low aeration unfavorable for germination and seedling development and to increased incidence of disease. Bulk Density and Soil Aeration The effect of continuous no-till corn production on soil compaction is not clear. Virginia workers (78) found that after 6 years of continuous no-till and conventional corn production, there was no significant difference in soil compaction between the two tillage systems. Researchers in Kentucky (15) found that after 5 years, no-till and conventional tillage treatments had nearly identical bulk density values at the 0 to 8 cm depth. Many researchers, however, have found higher levels of soil compaction in no-till fields. Gantzer, however, (30) found bulk densities averaged 10 percent higher within the surface 30 cm under no-till compared to conventional tillage. Bulk density differences due to tillage were not significant at depths greater than 30 cm. As the growing season progressed, the differences in surface bulk density between types of tillage were reduced because of increased densities under conventional tillage. Others have reported an increase in bulk densities under no-till (15,21,60,81). Bulk density increases with no-till are also supported by penetrometer data (44,60). Increased soil bulk densities can reduce yields by reducing root proliferation and changing root morphology (33). Increasing bulk density can also decrease the air-filled porosity and thus cause soil aeration problems. Air-filled porosities of surface samples are frequently lower in no-till soils. Gantzer (30) found that after 6 years of continuous nO-till corn production on a clay loam soil, air-filled porosities Of surface samples were lower under no-till than under conventional tillage at all water potentials measured. At -100 mb tension, no-till surface samples averaged 14 percent air-filled porosity compared to 20 percent for conventional tillage. After 3 years of no-till production in Michigan, A. E. Erickson (personal communication) found that air-filled porosities at -60 mb tension averaged 17 percent for plowed plots compared to 9 percent for no-till plots in a sandy loam soil. On a loam soil, conventional plots averaged 15 percent air-filled porosity compared to 10 percent for nO-till plots. Baeumer and Bakermans (5) have cited several researchers who found air-filled porosities of less than 10 percent at -100 mb tension with no-till on fine and medium textured soils. Air-filled porosity of 10 percent is a lower limit for most common crOps which are grown on drained land (100). Below this value oxygen diffusion is severly restricted and aeration conditions become unfavorable for germination and seedling development. Low yields in poorly-drained no-till fields in Minnesota and northern Illinois (49) were attributed to poor aeration conditions. Soil Aggregation NO-till and minimum tillage systems help to maintain and improve soil structure as evidenced by greater aggregation. Beale, Nutt, and Peele (9) compared plowed versus minimum tillage plots for 10 years. Soil aggregation in the surface 15 cm layer was substantially higher in minimum tillage plots than in plowed plots. Free (29) found higher aggregate stability in minimum tilled plots compared to conventionally tilled plots. In Indiana (18), minimum tillage resulted in more water-soluble aggregates than conventional tillage treatments. These results were attributed to the increased breakdown of aggregates due to conventional tillage rather than an improvement in aggregation in minimum tillage plots (20,82). Residues can protect soil aggregates from direct impact of raindrOps, and reduce slaking. As a result, soil crusting is less of a problem in no-till systems (42,43,76). Soil Temperature Crop residues on the soil surface usually reduce soil temperatures when compared to soils without surface cover. Residues reduce soil temperatures as a result of reflection of solar energy, insulation Of the soil surface and the greater heat capacity of the soil beneath the residue due to increased moisture. Studies in Kentucky (13) showed daytime maximum temperatures at a depth of 5 cm between 2.7 and 5.5 degrees (C) cooler while nighttime minimum temperatures averaged between 1.2 and 4.0 degrees warmer under no-till compared to adjacent tilled plots. These effects were magnified if a heavy mulch or a period of extremely dry weather occurred. After corn seedlings reached sufficient height to shade between the rows, no differnces in temperature were observed between no-tillage and conventional tillage. In Minnesota, Larson et al. (49) predicted that residue remaining from a6,300 kg/ha corn crOp reduces the 10 cm soil temperature by about 1.1 degrees (C), or about 0.4 degrees for each ton Of residue. Lower temperatures under crOp residues have been reported in many other locations (32,47,67). In northern areas the lower soil temperatures may inhibit germination and early growth (49). In southern climates and the trOpics, however, lower soil temperatures have little affect on yield (13,47). Effect Of Residues on Yields Differences in corn yields between nO-till and conventional systems are related to to the amount and type of mulch cover. In Ohio (49), on a crusting silt loam with no residue cover, no-till corn yields were less than a conventional treatment. With a complete mulch cover, yields from nO-till were greater than plowed treatments. The no-till corn yield advantage was greater following a fescue sod than corn because the sod resulted in a better mulch cover. On a silty clay loam, the amount of mulch cover or the type of tillage had no effect on yield. In Kentucky (13), yields were lower in treatments with a rye cover crOp than in treatments with no cover crOp because vigorous growth of the cover crOp in the Spring prior to being chemically killed removed some of the water reserve. In Delaware (59), eight cover crOps, killed before planting, were evaluated for no-tillage corn production. Treatments consisted of combinations of spring oats (Avena sativa 1L.),hairy vetch (Vicia villosa.Roth), crimson clover (Trifolium incarnatum L.), winter rye (Secale creale L.) and annual ryegrass (Lolium multiflorum Lam.). A surface mulch resulted in higher corn yields. Yields were generally higher under leguminous covers than beneath rye because of better stands, higher soil temperatures and increased available nitrogen. In Nigeria (47), crOp rotation in no-till was required to maintain adequate residue on the surface and to maximize 10 yields. Crops that did not leave a significant amount of residue on the soil surface could not be grown continuously without soil physical properties seriously deteriorating.. Nitrogen Transformations as Affected by Tillage and Residue The physical, biological, and chemical characteristics of no-till soils as compared to plowed soils explain the lower availability of N to 'plants under reduced tillage. Nitrogen availability is reduced because of more rapid downward movement of nitrate, lower rates of nitrification and mineralization, greater rates of N immobilization and greater losses of N through denitrification and volatilization. Reduced evaporation from the soil surface and increased water infiltration in no-till soils leads to increased water movement through the soil profile. Nitrate-nitrogen moves with the percolating water and is leached from the surface horizons. Thomas, et al. (87) found about half the nitrate-nitrogen was lost from the surface 15 cm Of soil under a surface nmlch, and a 50 percent gain in nitrate-nitrogen with conventional tilled soil. The higher soil moisture content in the no-till soils may have also led to increased denitrification and less mineralization of N (72). The tillage system may indirectly alter nitrogen availability by altering the microbial populations of the soil. Doran (21,22) has studied the soil microbial and biochemical changes associated with reduced tillage. He concluded that the changes in the physical characteristics of the surface of no-till soil compared to plowed soil result in large increases in all microbial groups in the qurface 7.5 cm: ll of no-till soils. This increase is a result of higher moisture and organic matter content in the surface of no-till soils. Deeper in the soil (7.5 to 15 cm), aerobic organism populations are 25 to 51 percent lower with nO-till than with plowing. Facultative anaerobes and denitrifers occur in greater numbers and represent a greater proportion of the total microbial pOpulation in no-till soils than in plowed soils. Consequently, the potential rate of mineralization and nitrification is higher with conventional tillage, while the rate Of denitrification is higher with no-till. The increase in microorganism population in the surface 7.5 cm of no-till soil leads to an increase in immobilization of 20 to 70 kg N/ha over plowed soils (8,11). Thus, a greater proportion of the fertilizer N, applied to the surface of no-till soils will be tied up in microbial cells. Lindeman et al. (52) studied the effects of tillage on soybean nodulation, acetylene reduction and seed yield. The no-till treatments had higher nodulation and acetylene reduction values than conventional tillage treatments early in the season and lower values in the last half of the season. Cumulative acetylene reduction and nodule weight was not affected by tillage. Yields were significantly lower in no-till treatments primarly due to weed competition. In addition to the potential for increased leaching, immobilization and denitrification, the potential for ammonia volatiliization is high in no-till corn production. There is greater potential for volatilization in nO-till systems because: (1) N fertilizers are usually not incorporated; (2) N is Often applied in solutions as a broadcast spray; and (3) organic matter accumulation and increased biological activity of the soil surface may stimulate urease 12 activity, insuring rapid enzymatic breakdown of urea (87). Researchers attribute the decreased efficiency of surface applied urea to volatilization (8,27,86,88). Fox and Hoffman (27) found that as much as 35 percent of surface applied urea is lost through this process. l3 Fertilizer Use Efficiency as Affected by Tillgge and Surface Residues N-Rate Studies Several potential N problems exist in no-till production. Early studies concentrated on the effect of N rate on yield, N uptake and N efficiency. Triplett and Van Doren (89) conducted one of the first no-till N fertilizer studies. Nitrogen as ammonium nitrate was applied to the soil surface at 67, 134 and 268 kg N/ha. The nitrogen was incorporated in plowed plots but left on the surface of no-till plots. Grain yields were higher for corn grown on the untilled treatments all 6 years of the study. Yields increased with the second increment of nitrogen on the untilled treatments but not on the conventional treatments. Nitrogen concentration of plant leaves was not affected by tillage method. Moschler, Marten and Shear (64,65) and Legg (51) also Obtained equivalent or higher yields under no-till as compared to conventional tillage when moisture was adequate. These studies showed equivalent or increased N recovery (N uptake plus soil N) under no-till as compared to conventional tillage. N recovery increases were primarily due to increases in organic N in the surface soil of the no-till treatments (15,62). The relative efficiency of N in no-till versus conventional treatments depends on the level of N fertilization. Moschler and Marten (62) observed lower N efficiencies on no-till treatments than on coventional tillage treatments at low N rates (67.3 and 201.8 kg N/ha). At a high N rate (470 kg N/ha), however, they observed lower N efficiency on the conventional treatments. l4 Moncrief and Schulte (60) Observed similar responses to N fertilizer. At low rates of broadcast N, corn yields and N uptake were less under no-till than under moldboard and chisel systems. At high rates, the differences in yield and N uptake decreased among the three tillage systems. At the highest N rate (336 kg/ha), yield and N uptake were higher on no-till treatments at several locations. Bandel et a1. (7) applied N to tillage treatments at rates Of 0,45,90,135 and 180 kg N/ha. At subOptimal N rates, N deficiency symptoms were more severe on no-till plots than on plowed plots. However, the Optimal rate for maximum corn yields was similar for both tillage methods. NO differences due to tillage were observed in the N status of the soil. N-Source Studies Ammonium nitrate was commonly used in early no-till fertility research because it is relatively non-volatile. Ammonium nitrate, however, is not the most commonly used N source in most corn-producing areas. Therefore, much research has been conducted to determine the influence of nitrogen source on N efficiency in no-till systems. Moschler and Jones (61) in Virginia and Bandel et al. (8) in Maryland compared the relative effectiveness of surface-applied ammonium nitrate, urea and urea-ammonium nitrate solution (UAN). Moschler and Jones observed that on both fertile and infertile soils, ammonium nitrate, urea and UAN were equally effective per unit of N applied. The two years of the experiment were relatively wet. Rainfall shortly after planting minimized volatilization losses from urea and UAN. Bandel et al. (8) noted a distinct relationship between rainfall 15 and the effectiveness of urea and UAN. At Poplar Hill, little differences between ammonium nitrate, urea and UAN was observed. Bandel attributed this to significant rainfall shortly after N application. At Wye Institute and Forage Research Farm ammonium nitrate was the most effective source during years when rainfall did not occur in the first few days after N application. UAN treatments in most cases slightly Out-yielded urea treatments. Fox and Hoffman (27) in Pennsylvania conducted experiments similar to Bandel et a1. Ammonium nitrate, urea, UAN and ammonium sulfate were applied at five rates to no-till corn plots. Yields and N uptake were highest for ammonium nitrate and ammonium sulfate and lowest with UAN and urea. Fox and Hoffman postulated the following relationship between rainfall and the effectiveness of urea and UAN: 1. There was insignificant N113 volatilization loss from unincorporated urea fertilizers if at least 10 mm Of rain fell within 48 hours after fertilizer application. 2. If 10 mm or more rain fell 3 days after the urea was applied, volatilization losses were slight ((101). 3. If 3 to 5 mm of rain fell within 5 days after the urea was applied, volatilization losses could be moderate (10 to 302). 4. If no rain fell within 6 days, the loss could be substantial (>302). Fox and Hoffman also recorded the surface pH for the 5 years of the study. The pH in the surface 2.5 cm of soil was approximately 5.7 in the plots receiving 202 kg/ha/yr of N as ammonium nitrate, urea or UAN. This pH was one unit lower than a check which had received no N 16 for the 5 years. In plots receiving the same rate of ammonium sulfate, the soil pH was 4.7 in the 0 to 2.5 cm layer. N-Placement Studies Bandel et al. (8) also studied N-placement. Bandel concluded that ". . . for nO-tillage, urea or urea solutions should be banded beneath the soil surface.” Several studies have indicated that urea and UAN placement methods may affect their performance. Mengel et al. (58) in Indiana found that injecting NH3 or UAN below the surface resulted in higher corn grain yields and higher N content in leaves than surface application of UAN, ammonium nitrate or urea. At a N rate of 165 kg N/ha, injection treatment yields averaged 8,600 kg/ha compared tn) 7,560 kg/ha for surface-applied treatments. The greater efficiency Of subsurface N fertilizer placement was attributed to reduced NH3 volatilization and reduced immobilization of N by soil organisms associated with the surface residues. Touchton and Hargrove (88) in Georgia also studied the effect of N sources and application methods on corn yield and N uptake. As in previous studies, the order of efficiency of surface-applied nitrogen fertilizers was generally ureaOH ummu afiom .N OHan I: «a N.~H m.~ mmm w~o.~ mm om N.n oqlom nw.m ma q.o~ ~.e Nmm mom.~ HHH no m.o owlo N w ooa\ma Ema BO .8qu 08 a: S mix 8 M Tampa me :38 Ofiamwuo manmuomuuxm OHnmowcmsuxm .%e=um omeHHu :uOO map How mHo>OH ummu Hfiom .H manna 31 mesh screen using a Wiley mill. Grain samples were ground to pass through a 20 mesh screen. Duplicate samples from each plot were digested by a modified version of the wet oxidation procedure described by Parkinson and Allen. (68). The digestion solution was prepared by mixing 350 ml of H202, 0.42 g Se powder and l4 g L12804°Hzo in a flat bottomed boiling flask. Concentrated H2804 (420 ml) was added carefully with swirling and cooling. Plant samples (0.5 g) were weighed into 100 ml round bottom-long neck reflux flasks; 5 ml of digesting mixture were added, and the samples digested on electric heaters for 3 hours. At the end of the digestion, the solutions were allowed to cool and were then diluted to 35 ml with 1000 ppm LiCl. For nitrogen analysis, a 1.0 ml aliquot of sample solution w a s pipetted into a 100 ml micro-Kjeldal flask. Ten ml of 1.0 N NaOH and 15 ml distilled water were added and the solution was distilled until 30 ml was collected in a flask containg 5 ml of boric acid (21) and methyl purple indicator. The samples were titrated with standardized H2804. Determination of P, K, Ca, Mg, Fe, Zn, Mn, Cu, and Al concentrations were made with a SMI IIIA direct current plasma emmission unit. A one to ten dilution of the digested samples was necessary for the K, Ca and Mg analysis. 32 Soil Physical Properties Soil Temperature and Moisture Soil temperature measurements were made in both studies on May 17. Four measurements were made in each tillage whole plot. All measurements were made at 10 cm in depth between 14:00 and 15:00 P.M. Tensiometers and a neutron probe were used to monitor soil moisture content in each of the 8 tillage whole plots in each study. Tensiometers were installed in the row at a depth of 30 cm and were read 3 times per week. Neutron probe access tubes were installed in the row to a depth of 61 cm. Soil moisture was determined using a Campbell Pacific Nuclear Corporation neutron probe (Model 503 hydrOprobe). Readings were taken once a week at 15.2, 30.5 and 45.7 cm depths. Percent Residue Cover Surface residue cover in the soybean study was estimated by the photographic method outlined by Mannering (54). A wood frame with inside dimensions of 76 cm by 51 cm was placed on the soil surface in 6 locations in the no-till areas. Pictures of the frame and residue were taken at each location. The images were projected over a grid and the percent cover was estimated by an intersection procedure. Bulk Density and Air-Filled Porosity Bulk density and air-filled porosity were determined by the methods described by Blake (12) and Vomocil (96). Five undisturbed soil cores were taken from the surface 7.62 cm of soil in each of the tillage 33 whole plots in the corn study on July 1. The cores were saturated, weighed and then placed in a pressure plate apparatus. The soil was subjected sequentially to .01, .02, .03, .04, .06, .1, .33 and 1.0 bar pressure. When water was no longer moving out at a given pressure, the cores were weighed and moved to the next higher pressure. After exposure to 1.0 bar pressure, the cores were oven dried (104 C for 24 hours) and then weighed. Air filled porosity at a given pressure was determined using the equation Vb where "U I p percent air filled pore space at pressure p Vb" bulk volume of the core in milliliters W8 z mass of saturated sample in grams S 'O I mass of sample in grams after drainage at pressure p Root Distribution Root samples were taken on September 14 to determine the effect of tillage system on corn root distribution. A mechanical sampler was used to extract undisturbed soil samples (7.6 cm wide by 25.4 cm long by 61.0 cm deep). One core was taken from each tillage whole plot. Each large sample was divided into 18 subsamples (7,6 by 7.4 by 7.6 cm) with a fractionating cutter. This made it possible to analzye corn root lengths at 6 depths and 3 distances away from the row. The sampling method is described in detail by Srivastava et al. (83). Subsamples were dispersed by soaking them in water containing 50 g per liter of (NaPO3)6 for a period of 16 hours. Roots were seperated 34 from the soil by the hydrOpneumatic elutriation system described by Smucker et al. (80). Root length density was determined for each subsample by the intersection method described by Newman (66). Statistical Analysis Statistical analysis was performed as described by Steel and Torrie (85). Analysis of variance of experimental data wasidone with a Cyber 750 computer using the Genstat statistical package (1). RESULTS AND DISCUSSION Field Conditions and Soil Physical Properties as Affected by Tillgge Field Conditions at Planti‘njg The 1982 growing season was characterized by an extremely warm, dry Spring followed by average temperatures and rainfall in the Summer and Fall. Total rainfall for the corn growing season was 40 cm. At planting, field conditions varied considerably between tillage systems. In the corn study, the conventional plots were cloddy at planting due to Spring plowing and inadequate secondary tillage. Poor seed-soil contact and extremely dry, compact soil conditions hindered germination in these plots. Better moisture conditions existed in the no-till plots at planting resulting in uniform germination. The percent of late germinating plants in the conventionally tilled plots was more than double that of nO-till plots (Table 3). The final plant pOpulation and percent barren stalks, however, were not significantly different between the two tillage systems. In the soybean study, dry, compact soil conditions at planting and an uneven soil surface created by the corn stubble led to non-uniform seed and fertilizer placement in no-till plots. Some seeds remained on the soil surface. As a result, final populations were significantly lower in no-till plots (Table 4). No-till plots averaged 17 percent fewer plants than conventional plots. The loss in pOpulation was Observed for both varieties. The problem Of inadequate seed and 35 36 Table 3. Effect of tillage on germination, final corn population and percentage of barren stalks. Late Final corn Barren germination population stalks Z plants/ha Z Conventional 16.3 77,140 3.6 No-till 7.2 79,410 2.9 LSD (.05) (5.0) (NS) (NS) Table 4. Soybean plant population as affected by tillage and variety. Variety Tillage method Corsoy 79 SRF-200 Mean LSD (.05) --plants per hectare-- Conventional 340,000 . 344,000 342,000 (34,000) No-till 287,000 282,000 284,500 Mean 313,000 313,000 LSD (.05) (NS) 37 fertilizer placementcould have been reduced by using a heavier planter equiped with more effective coulters and by planting parallel to the corn rows. Cloddy field conditions could have been avoided by plowing in the Fall when the soil was drier. Soil Temperature Surface residue in the no-till plots did not reduce soil temperatures enough to affect emergence in either study. In the soybean study, 60 percent of the surface of the no-till plots was covered with corn residue; however, soil temperature at planting was only slightly lower in no-till plots (22 C) than in the conventional plots (24 C). Because of the unseasonably high soil temperatures, no differences in time of emergence were observed between the two tillage systems. In the corn study, very little surface cover remained on the no-till plots after the rye cover crOp was killed. Unseasonably warm conditions at planting allowed for rapid germination and emergence in the no-till corn plots. In years with cooler Spring temperatures reduced soil temperatures under the surface residue have been found to delay germination and emergence in no-till plots (13,49). Soil Moisture In nonirrigated studies the presence of a surface mulch has been found to significantly affect the soil moisture content and distribution (13,14,35,99). In these irrigated studies, differences in soil water content between the two tillage systems were not evident. Tensiometer readings for the corn and soybean studies are shown in Figure 1 and 2. Only slight differences in tensiometer readings occurred between the two 38 couveurtount No-TILL 100 (DDUD-HOZ “z UUZI—HQCKW 110 120 100 DHYS flFTER EHEROENCE 90 Figure 1. Corn study tensiometer readings at 30 cm as affected by time and tillage. 80 70 60 39 o: .N shaman .omeHfiu mam mafia he emuoowum mm Eu.om um mwcwvmou nouoEmeaou monum :mmnxom wuzwcmuzm aura «:3 2: cm on or om om ow b _ _ _ _ _ o ...s .... .... .... . T ON .u T a. ... s\ u. a. ... .. r 8 1 cm .3262 ....-. .Ezozzgzoo ll. Oo— 03:3£JF-fi‘c325 LJMUIKF-h‘flflctflfiab 40 tillage systems. Peaks om.these figures represent periods of low soil moisture contents. Low suction values occurred after rainfall or irrigation. Tensiometer readings seldom exceeded 60 centibars suction indicating that rainfall and/or irrigation was adequate to avoid extended periods of water stress. Soil water content as measured by the neutron probe at 15, 30 and 46 cm in depth are shown in Figures 3-8. Fluctuations in soil water content as measured by the neutron probe correspond well to tensiometer readings (Figure 1 and 2). Greater fluctuations in soil water content occurred at the 15 cm depth than at 30 or 46 cm. Soil water content was not significantly affected by tillage method in either study at any of the depths measured. In both the corn and soybean study, there was a significant interaction between tillage and depth in soil water content. In the corn study (Figure 9) the average soil water content at 15 cm was similar for the two tillage treatments. In conventional plots, the soil moisture at 30 and 46 cm was less than at 15 cm. In no-till plots soil moisture was higher at 46 cm than at 15 and 30 cm. In the soybean study, moisture content in both tillage systems increased slightly with increasing depth (Figure 10) This increase was more pronounced in the conventional treatment than in the no-till treatment. These differences in moisture distribution may be due to differences in root distribution, infiltration, soil variability or water holding capacity in the two tillage systems (6,13). 41 .uwaum cuoo wmmeHHu up mouommum mm canoe Eu ma um.mWEO\wv Hwom mo acoucoo Houma Owuuoasao> uuzuozmzu em a: m>co :2 8” o: 2: 8 8 2. 8 S 3 _ _ _ _ b . _ _ .— i all \ao Ilia o sssuaanaonaaan. If r 000’...- \ \ O '00 coo N. 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Emma m on m. a. an on ma as no as — — — — _ _ — uN cl r m.& r «N .......... ......-m m .......... r méu a \\ a... r 8 h z m .. 98 u e u T N ._ a..2..ozd.-.g $225228: fi T 93.. - r ON 48 .Avaum somehow EO\OV gonna Haom mo sowuaaauumwn MOOOHHAO ha vmuooOOo mm sumac Ou uooamou now: A .zu. gamma" on m. a. an on mm on we as — — b — _ — — T l-I—fl #892 no...” aczoaezu>zouarla r 80‘8880‘083 I r W F T .OH ouzmfim «N 0.0N NN O.NN ON 0.0N cN O.vN ON O.hJO§¢)hJIBF- :ICBh-MJQ: 49 Bulk Density and Soil Aeration Tillage method significantly affected both bulk density and air-filled porosity in the corn study. Bulk densities of the surface soil (0-8 cm) averaged 1.18 g/cm3in the conventional tillage treatment and 1.33 g/cm3 in the no-till treatment. These results support the findings of Gantzer (30) and Others (15,21,60,81). Aeration porosity of surface samples (0-8 cm) taken from the two tillage treatments is shown in Figure 11. A consequence of the increased soil bulk density in no-till plots was that air-filled porosity in no-till plots was less than in conventional plots at all potentials measured. These results are in agreement with the works of Gantzer (30) and A. E. Erickson (personal communication). The aeration. porosity results indicate that there are fewer large pores in the untilled soil (81,99). The air-filled pore space exceeded 10 percent at all but the 10 cm suction; therefore, according to the findings of Wesseling and van Wijk (100), aeration was probably not a problem in either system in this study. Yields Corn Corn grain yields, averaged over the two harvest dates, are shown in Table 5. Only the main effects of tillage method and nitrogen rate were found to be significant at the 95 percent confidence level. The highest yields were obtained in the no-till treatments which received 336 kg N/ha. Lower yields in the conventional treatments are attributed mainly to later germination. Final plant pOpulations and the percentage of barren stalks were similar for the two tillage systems, but plants in 50 .xuaum OOOHHHO :uOO OH AEO OIOV Hwom oumwunm mo zuwmouoa cofiumuom co muoommm mmeHHH Amp—O: to .zoZOOOIO OOJ OJ OJ *4 N.“ O.N O.N . v.N _ N.N _ N — Pl ...—Ohio: ...--- AOZOthw>2OO ..Il on On .HH opsmae OLMJOIL3hJZEF- ¢B**fl: h.h‘_J_JhJC3 O.€305hJ ODD-OELJDJ 51 Table 5. Corn grain yield as affected by tillage method, nitrogen and potassium rate and phosphorus placement. N P K Tillage method LSD rate placement rate Conventional No-till Mean (.05) kg/ha kg/ha -------- kg/ha2----—--- 168 Broadcast 56 12,030 12,310 12,170 168 168 11,640 12,100 11,870 336 56 12,200 12,560 12,380 336 168 12,040 12,920 12,480 168 Banded 56 11,700 12,190 11,940 168 168 12,010 12,840 12,430 336 56 12,160 13,140 12,650 336 168 12,130 12,550 12,340 Overall means Tillage 11,990 12,580 (390) Nitrogen rate 168 kg N/ha 12,100 (230) 336 kg N/ha 12,460 Phosphorus placement Broadcast 12,220 (NS) Banded 12,340 Potassium rate 56 kg K20/ha 12,290 (NS) 168 kg K20/ha 12,280 lPhosphorus rate = 56 kg P 0 2 5 per hectare. 2Adjusted to 15.5% moisture. 52 conventional tillage plots, which had emerged several weeks late, were tall and spindly compared to early emerging plants. The late germinating plants in the conventional plots were also subject to silk pruning by corn rootworm beetles (Diabrotica virgifera Le Conte). Good yields were obtained with 168 kg N/ha, and only a moderate yield increase occurred with an additional 168 kg N/ha. Grain yield was 'not affected by the placement of phosphorus or the addition of potassium; this was probably due to the high initial levels of these nutrients in this field (Table 1). Grain moisture at harvest was significantly lower in nO-till plots (Table 6). Nitrogen rate did not appear to affect grain moisture in the nO-till plots; however, in conventional plots, the high nitrogen treatments had significantly lower grain moisture than the low nitrogen treatments. Neither phosphorus placement nor potassium rate had any affect on the moisture content of grain. Stover yields were not affected by tillage method, phosphorus placement or potassium rates (Table 7). The high N rate (336 kg/ha), however, significantly increased stover yield. Soybean Soybean yield data is presented in Table 8. Excellent yields were Obtained even though severe lodging occurred in all plots as a result of a heavy shower on July 26 and high intensity irrigation. Despite the severe lodging, harvest losses were small. Phytophthora root rot (Phytophthora mega_spermavar 22.133) caused some yield reduction in the SRF-200 variety in low lying areas, but did not appearto be related to a particular tillage treatment. Grain yields were not affected by tillage 53 Table 6. Corn grain moisture at harvest (October 18) as affected by tillage method and nitrogen rate. Tillage Nitrogen rate (kg/ha) method 168 336 Mean LSD (.05) ----- Z moisture------ Conventional 28.5 27.3 27.9 (1.4) No-till 25.0 25.0 25.0 Mean 26.8 26.2 LSD (.05) (0.6) 54 Table 7. Corn stover yield as affected by tillage method, nitrogen and potassium rate and phosphorus placement. N P K Tillage method LSD rate placement rate Conventional No-till Mean (.05) kg/ha kg/ha -------- kg/ha --------- 168 Broadcast 56 9,380 8,789 9,085 168 168 8,975 8,909 8,942 336 56 9,898 9,118 9,458 336 168 9,963 9,826 9,895 168 Banded 56 9,593 8,724 9,159 168 168 9,316 9,132 9,224 336 56 9,493 9,402 9,447 336 168 10,554 9,455 10,004 Overall means Tillage 9,634 9,169 (NS) Nitrogen rate 168 kg N/ha 9,102 (363) 336 kg N/ha 9,701 Phosphorus placement Broadcast 9,345 (NS) Banded 9,459 Potassium rate 56 kg KZO/ha 9,287 (NS) 168 kg KZO/ha 9,516 1Phosphorus rate 56 kg P per hectare. 55 Table 8. Soybean yield as affected by tillage method, variety, phosphorus placement and potassium fertilization. P K Tillage method LSD Variety placement rate Conventional No-till Mean (.05) kg/ha -------- kg/ha1 -------- Corsoy 79 Broadcast 0 4,409 4,543 4,476 Corsoy 79 56 4,460 4,303 4,381 SRF—200 0 4,354 4,258 4,306 SRF-200 56 4,163 4,070 4,117 Corsoy 79 Banded 0 4,479 4,452 4,465 Corsoy 79 56 4,497 4,409 4,403 SRF—200 0 4,132 4,043 4,087 SRF—200 56 4,156 3,876 4,016 Overall means Tillage 4,319 4,244 (NS) Variety Corsoy 79 4,431 (136) SRF-200 4,131 Phosphorus Broadcast 4,320 (NS) Placement Banded 4,243 Potassium rate 0 kg K20/ha 4,334 (NS) 56 kg K20/ha 4,229 lAdjusted to 13% moisture. 2Phosphorus rate = 56 kg P205 per hectare. 56 ‘method. These results support the observation that soybeans can compensate for poor initial stands. The yield of Corsoy 79 was significantly higher than SRF-200. Yield was unaffected by the placement of phosphorus or the addition of potassium; this was probably due to the high initial levels of these nutrients in this field (Table 2). Grain moisture at harvest, although not reported here, was unaffected by any of the treatments. Plant Analysis Corn The main effects of tillage and fertilizer treatments on the elemental composition of whole corn plants taken at the early whorl stage, ear leaf samples taken at silking and grain and stover sampled at harvest are presented in Tables 9-12. Significant treatment interactions are presented in Tables 13-15. Tables 2a-5a in the appendix show the elemental analysis for the individual treatments. At the early whorl stage, N content of the whole corn plants was significantly higher in the nO-till plots than the conventional plots (Table 9). After this sampling, the additional 168 kg N/ha was applied to the high N treatment. The topdressing of additional nitrogen resulted in higher ear leaf, grain and stover N content (Tables 10, 11 and 12). No-till ear leaf, grain and stover samples had lower N content than samples from conventional treatments (Tables 10, 11 and 12). Corn grain from no-till plots had significantly lower levels Of N than grain from conventional plots at the low N rate, but about the same concentration as conventional plots at the high N rate (Table 13). 57 .oumuoon Hon O m ON on u mum“ mauosamonm m N H Hmzv Amzv Amzv Amzv Amzv ANo.V Amo.v Amzv Hmzv Amzv no.v amH omN.H NH He OON.H ma om. HN. sm.m Ne. mo.s 6e\o w we NOH oNN.H NH He oNN.H me am. ON. om.m me. OH.e 6e\o M we om "Oumu Bdfimmmuom Hmzv Hmzv Hmzv Hmzv Hmzv Hmzv Hmzv Hmzv Hmzv Amzv Amo.v amH oNN.H NH He oNH.H Na mm. NN. mm.m ms. NH.s smegma oom.H NH He omN.H mm mm. ON. oa.m Ne. oH.e ummoemopm "Huamamumam msuonamonm HNmHV Amzv Hmzv ANNNV ANNV Hmzv Hmzv Hmzv Heo.v AHN.V Hmo.v amH pomN.H NH NN omm «N as. HN. om.m as. ON.s HHHuioz momm.N NH ms omm.H eHH mm. 3N. Na.m an. mm.m HmeoHuam>aoo “omeHHN Ema N H< so aN we a: N: no a N z usaaummpe unoEOHm .ucoEOOOHQ mononmmonm wan coaumNHHfiuuom asfimmmuoa Ono cowouufi: .OOSOOa OOOHHHO An wouuowmm mm Aowmum duosa Naumov mucmam OH053 mo coaufimomaoo Hmucoaoam .m manna 58 .oumuoos you O m Ox om u mum“ mayonnmosm m N H Hmzv Hmzv Amzv ANNV szv HHo.V Hmzv Hmzv Amzv Amzv No.v mmH on NH He sNN NO ON. NN. N.N NN. NH.N me\o m we NNH NN NH NN NNN He NN. ow. O.N NN. NH.N ae\o N we on "mama fiafimmmuom Hmzv Hmzv Hmzv Amzv Amzv Hmzv Hmzv Hmzv Hmzv ANo.V Ano.v amH NN NH NN HON He NN. NN. O.N NN. No.N Novena NN NH He NNN Ne NN. om. N.N ON. NH.N ammoemoom "Hudoamomaa mauonamonm Hmzv Hmzv Hmzv Hmzv ANV Hmzv Hmzv Hmzv Amzv Amo.v Ano.v nNH NN NH oe «NN N3 NN. ow. N.N NN. NH.N me\z we NNN an NH NN «ON NN NN. NN. N.N NN. No.N 6e\z Na NNH "sump nowouuwz Hmzv Hmzv Amzv AeHV Amzv Aso.v Aso.v Amzv Amzv ANo.v Amo.v amH Ne NH NN NON NN NN. NN. N.N NN. 0H.N HHHunoz so NH Ne NNN ms NN. NN. N.N NN. NH.N HaaoHH=o>aou "OOOHHNH BOO N He no cN as ex N: we N N z Hamsummpa uGOEOHm .uaoaoomaa msuonmmoca was cowumnaafiqum aswmmmuoq mam amwouufia .Oosuoa owmaafiu an wouoommm mm AOONMHNO Naumov wmoa umo cuoo mo OONONOOOEOO Hmuaoamam .OH manna 59 .oumuoo: Hon m ON on a monk mauonnmonm H Hmzv Amzv Hmzv Amzv Hmzv Amzv Amzv Hmzv Hmzv No.v NNH as O.N NN NN N.N HN. on. NN. Hs.H me\o m we NNH om N.N NN NN N.N NN. on. NN. Ns.H me\o N we on "mumu sawmmmuom Hmzv Hmzv Hmzv Amzv Hmzv Amzv Hmzv Hmzv Amzv Amo.v NNH as o.N «N NN H.e NN. HN. NN. Ns.H emeemm om N.N NN NN N.N HN. as. «N. Hs.H ammoemoum "Hucoaoomao msuocamonm Hmzv Amzv Amzv Hmzv Hmzv Hmzv Hmzv Hmzv AHo.v Amo.v NNH as N.N NN NN N.N NN. on. «N. Ne.H me\z we NNN as N.N NN NN N.N HN. om. NN. NN.H ae\z we NNH ”Oumu sowouuaz Hmzv Hmzv Amzv Hmzv Hmzv Amzv Hmzv Amzv ANo.V Ano.v NNH Ne N.N «N NN N.N HN. Ne. NN. oe.H HHHunoz as O.N NN NN N.N NN. on. «N. as.H HaeoHuao>eoo "OOOHHNH Ema N H< so cN mN a: w: M N z acmsumuue ucoamam van mowouuN: .Oonuoa omeHNu an Omuuowmm mm :Nmuw auoo mo OOHuNOOAEOO HmucoaOHm .uaosoomaa mauosamosa can coaumnaawuuom Baammmuom .HH oHnmN 60 .oumuooz Hon nomm ON on u Oumu msuosmmonm H ANzO HNzO ANzO HNzO ANzO AN0.0 HNzO AOH.O HNO0.0 AN0.0 N0.0 ONH NOH 0.0 NH OON ON ON. NN. NO.H ONO. NN. NO\O m NO NOH OOH N.O OH NON ON ON. HO. NO.H ONO. HN. NO\O M NO ON ”some abfimmmuom HNzO ANzO ANO ANzO ANzO ANzO ANzO ANzO HNzO ANzO AN0.0 ONH NNH 0.0 NH OHN NN NN. OO. NO.H NNO. ON. OOOONN ONH N.O OH HON NN ON. NN. OO.H ONO. NN. ONNOONONN “Huaoamoman msuonmmoem HNzO ANzO ANO AONO ANO HN0.0 AN0.0 ANzO ANzO HN0.0 AN0.0 ONH NNH 0.0 NH NNN NN NN. NO. OO.H ONO. ON. NO\z Ne ONN ONH N.O OH ONN NN NN. ON. OO.H ONO. OO. me\z Ne NOH "sump sowouuwz ANzO ANzO HNzO ANzO ANzO ANzO HNzO ANN.O ANzO HO0.0 HN0.0 ONH OOH N.O NH NNN ON ON. ON. NO.H NNO. ON. HHHOuoz OOH N.O NH NNN ON NN. OO. NN.H NNO. ON. HNOOHOOO>OOO "OOOHHNH Ema N H< OO ON ON a: N: NO N N z Osmaummue ucosoam .ucosoomHO mayonamonm vcm OONOONNHNOHOO EOHOOOOOO van cowouuwc .vonuoa omeHNu Na wouuommm mm uo>oum auoo mo OONuNmOOBOO Hmuaoaoam .NH OHOOH 61 Table 13. Effect of tillage and nitrogen fertilizer on the elemental composition of corn grain (interaction effects). Concentration Tillage N-rate N P. K Zn kg/ha — — Z ppm Conventional 168 1.41 .332 .484 21.7 336 1.47 .353 .520 23.8 No-till 168 1.34 .368 .515 24.8 336 1.46 .329 .472 22.8 LSD (.05) (.03) (.024) (NS) (NS) Table 144 Effect of nitrogen and potassium fertilization on the elemental composition of corn grain (interaction effects). Concentration N-rate K-rate P K kg/ha ----------- Z 168 56 .339 .486 168 168 .362 .512 336 S6 .352 .512 336 168 .331 .481 LSD (.05) (.030) (NS) 62 Table 15. Effect of tillage and potassium fertilization on the elemental composition of corn stover (interaction effects). Concentration Tillage K—rate Mn kg/ha ppm Conventional 56 23 168 . 25 No-till 56 27 168 23 LSD (.05) (NS) 63 These results are similar to those observed by Moschler and Marten (62) and Moncrief and Schulte (60). Higher levels of N were observed in ear leaf samples from the broadcast phosphorus treatments when compared to banded, but the data cannot be explained. No severe deficiency symptoms, however, occurred in any plots. Nitrogen deficiency symptoms late in the season were more apparent in no-till plots particularly at the low N rate. These results are similar to those of Bandel et a1. (7) who observed that at suboptimal N rates, N deficiency symptoms were more severe on no-till plots than on plowed plots. Phosphorus levels in whole plant samples were significantly higher in no-till plots than conventional tilled plots, but the differences were not present in the ear leaf at silking or in the grain and stover at harvest. Greater P concentration in no-till plants at early samplings have been noted by several researchers (65,78,89). These researchers concluded that better moisture conditions in no-till plots may enhance P uptake. In this study, soil moisture measurements were not made early enough in the growing season to substantiate this conclusion. The method of P placement had no effect on the P composition of any plant tissues or grain in either tillage system. The high rate of K fertilization appeared to decrease the P content in corn stover, but K rate had no affect on the P content in early whole plant, ear leaf or grain samples. A significant nitrogen by tillage interaction was observed for the P content of grain (Table 13). Nitrogen topdressing increased the P content of corn grain in conventional treatments but decreased P content of corn grain in no-till treatments. There was also a significant N by K rate interation on P 64 content of grain (Table 14). At the low N rate, P content was higher at the high K rate than at the low K rate. At the high N rate, P content was higher at the low K rate. The K concentration of stover was found to be significantly lower in the no-till plots than in conventional plots (Table 12). The stover appeared to dry down faster in the no-till treatments. Therefore, the lower levels of K in stover in no-till treatments may reflect higher amounts of K leaching from the senescing plant tissue. The high rate of K fertilization resulted in increased K content of corn stover (Table 12). The K content of early whole plants and ear leaf samples was not affected by tillage. A significant N rate by tillage interaction for K. in grain was observed (Table 13). Nitrogen topdressing increased the K content of corn grain in conventional treatments but decreased K content of corn grain in no-till treatments. The N by K rate interaction for K content of corn grain was significant (Table 14). At the low N rate, KL content was higher at the high K rate than at the low K rate. At the high N rate, K content was higher at the low K rate. Calcium and Mg content of ear leaf samples at early silking was significantly higher in the no-till treatment than in the conventional treatment (Table 10). The differences did not carry through to grain and stover at harvest. The treatments with high rates of K fertilization had significantly lower levels of Ca and Mg at the early whorl stage and significantly lower Mg in ear leaf samples at silking and in stover at harvest.As the K concentration in the plant or grain increased Ca and Mg concentrations decreased. This is a well known occurrence due to the competitive effect which K exhibits on Ca and Mg uptake. 65 The levels of micronutrients in all treatments were well above the critical concentrations required for Optimum corn production (38,95). Differences in micronutrient composition between tillage methods were significant at the first sampling with no-till treatments having lower aoncentpations of Mn, Fe and Al than conventional treatments (Table 9). No-till treatments also had lower Fe concentrations in leaf tissue at early silking (Table 10). When N was topdressed higher levels of Mn, Zn and Cu and lower levels of Fe were observed in corn stover (Table 12). The increase in Mn uptake with increasing N rate has also been observed by Lal (48) and Lutz and Lillard (53). The method of P placement and K rate had little influence on the concentration of trace elements. Zinc content of corn stover was higher with banded P than with broadcast P. The Fe content of ear leaf samples at silking were lower at the low K rate than at the high K rate. A significant nitrogen by tillage interaction was observed for Zn in grain (Table 13). Nitrogen topdressing increased the Zn content of corn grain in conventional treatments but decreased Zn content of grain in no-till treatments. A significant K rate by tillage interaction was observed for Mn in corn stover (Table 15). In conventional plots Mn content was higher at the high K rate than at the low K rate. In no-till plots Mn content of stover was higher at the low K rate. Soybean Elemental composition of soybean leaf and grain are presented in Tables 16 and 17. Tables 7a and 8a in the appendix give the elemental analysis for the individual treatments. Nitrogen composition of leaf samples taken at early bloom was greater in no-till treatments than 66 .mumuomn you mon wx on n sump mayonnmonm H NNzO NNzO NNzO NNzO NNzO NN0.0 ANzO NNzO NNzO ANzO N O.V ONH NN OH NN NNH ON HN. HN.H NN.N OO. NN.N mONO m NO ON NN NH OO HNH NN NN. NN.H NN.N NO. NH.N OONO O NO O ”mu—NH EQfimmMuom NNzO NNzO NNzO NNzO NNzO NNzO NNzO NNzO NNzO NNzO NN0.0 ONH NN OH NN HNH NN NN. NN.H NN.N OO. NH.N ONOOOO NN OH OO NNH ON ON. NN.H NN.N NO. NN.N ummucmoum “Huamawoman mayonnmonm NNzO NNzO NNzV NNzO NOV NNzO AN0.0 NNzO NNzO NNzO NN0.0 ONH ON NH HO OON OO NN. NH.H ON.N OO. NH.N OONIONN HN NH NN NNH NN NN. NN.H NN.N NO. HN.N NN Nomuou “muowum> NNzO NNzO NNzO NNzV NNzO NNzO NNzO ANzO NNzO NNH.O ANO.V ONH NN OH NO NNH OO NN. NN.H HN.N NO. NN.N HHHuuoz NN OH NN ONH HN NN. HN.H NN.N OO. OH.N HNOOHuOo>OoO "ONNHHHH I Baa IN HO NO ON OO O: N: NO x O z Oauaummue ucmEmHm .soaumufiafiuuom adfimmMuom mam unmamomaa mauonmmosn .Nuowum> .coSums omeHHu Na wouommmm mm Aaooan Naumov wmoa amonhom mo coaufimoaaoo Housmamam .oa macaw 67 .mumuoon use momm w& on n mumu mauosmmonm H NNzO NNzO NNzO ANzO ANzO NNzO NNzO Nsz NNzO NNzO NM0.0 ONH NH OH OO NN NN NH. HH. ON.H NN. NN.O OONO M NO ON ON OH OO ON HN NH. HH. NN.H NN. NN.O OONO O NO O “mama anammmuom NNzO NNzO NNzO NNzO NNzO NH0.0 NNzO NNzO Asz NNzO NN0.0 ONH NH OH OO NN NN NH. HH. ON.H NN. NN.O ONOOON NH OH OO NN HN NH. HH. NN.H NN. ON.O ONOOOOOON "Hucoamoman mayonnmonm NNzO NNzO NNzO Nsz NNzO NH0.0 ANzO NNzO NH0.0 NN0.0 NN0.0 ONH OH NH OO ON NN NH. HH. ON.H NN. NN.O OON-NON NH OH OO NN HN NH. HH. NN.H NN. O0.0 NN NONNOO "Nuoaum> ANzO NNzO NNzO NNzO NNzO NNzV NNzO NNzO NNzO NNzO AN0.0 ONH OH OH OO NN NN NH. OH. NN.H HN. NN.O HHHunoz NN OH OO NN HN NH. HH. NN.H ON. ON.O HOOOHOON>OOO "NNOHHHO 8am N I HO ON ON ON O: (NO OO O N z OOOOOONNN uswsmam .cofiumNNHNuumm azfimmmuoa mam uamaoomaa wsuonamosa .Nuoaump .wonuoa mmeHHu an wouommmm mm camuw ammnhom mo :oHuNmonEoo Hauaoawam .NH magma 68 conventional treatments. These differences did not carry through to the grain at harvest. Corsoy 79 had significantly more nitrogen in the grain than SRF-200. Phosphorus and potassium concentrations were not affected by tillage or fertilizer treatments. The P content of grain was significantly higher in the Corsoy 79 than in the SRF-ZOO. Leaf Ca at early bloom was significantly higher in the Corsoy-79 variety. Leaf Mg content was higher in the SRF-200 variety than in the Corsoy 79. The Mg content of grain was also higher in the treatment receiving no K fertilizer than in the treatment that received K fertilizer. Micronutrient levels in soybean leaves at early bloom and grain at harvest were similar regardless of tillage or fertilizer treatment. The SRF-ZOO had a significantly higher level of Mn than Corsoy 79 in the leaf tissue at early bloom. Root Density Corn root densities were not altered by tillage (Figure 12, Table 18). In both tillage systems, highest root densities occurred in the surface 7.6 cm of soil. Root densities decreased with increasing depth and with increasing distance away from the row. These result contradict the findings of Barber (6), Phillips et al. (69) and Kang and Yunusa who found that tillage significantly affected the distribution of corn roots with respect to depth. Rooting patterns were probably similar for both tillage treatments in this study because of similar moisture regimes under the two tillage treatments. During sampling, roots were observed at depths below those taken for analysis (45.7 cm). Many of these deep roots were growing through worm channels. .oE=Ho> HNom Has: uma :uwawH uoou cuoo co nuemv wow mumHHNu mo mucosamcw .NH whamwm zuipbo om mv ov mm on mu ow ma 3 m p _ _ _ _ _ _ _ H . .3 w m u r N m c u T N.N » .— H m u m m a ....Zuozo.--o I . .n—O $235329on m m o a 7O .uaoaummuu mmeHNu mamm onu nuas Noocmumac ucmuowwfiv um moaufimamv wcaumaaoo pom A $5 GE GE GE 8.: 8.: NO; ONH Amzv H.H N.O N.N m.H O.N O.N N.mO Amzv m. O.N m.H m.a m.~ N.N H.mm Amzv N.N m.H N.N N.N w.H m.m m.om Amzv o.m N.N N.N m.~ m.~ H.m w.- Aw.Hv m.N O.N N.N O.N ~.m o.O ~.mH Aw.HV O.N N.N N.N N.N o.O m.O O.N Illoo\ao Bo Ano.v an Haauloz Hmaoauco>cou HHHuloz Hmcoauco>aoo HHNuloz Hmcoausopcou suave H . . . w NN N ma 0 N AEUV 30H Scum mocmuman .3ou aoum moamumwv van Sumac .mmeHNu Np wouommmm mm Nufimamv nuwcma uoou choc .wH MHQNH Summary and Conclusions High corn and soybean yields were obtained in no-till systems on medium textured soils. The climatic conditions of the 1982 growing season were nearly ideal for no-till crop production. The warm, dry Spring allowed for early planting and uniform seed germination and plant emergence. During a cooler Spring, reduced temperatures under the surface mulch may delay emergence and reduce yields in no-till systems. Lower corn yields occurred in conventionally tilled plots because of dry moisture conditions at planting which delayed germination. This jproblem.was eliminated in the soybean study by irrigating shortly after planting. Soybean stands were lower in no-till plots because of nonuniform seed depth at planting, but yields were not affected by the tillage method. In previous research, reduced nutrient availability in no-till has been attributed to the low mobility of surface applied P and K. In these studies, however, macro and micronutrient availability appeared to be similar in both tillage systems as evidenced by yield and nutrient composition data. Nitrogen and P uptake early in the season was be higher under no-till than under conventional tillage. The method of P placement and the K rate had little influence on corn or soybean yields or nutrient compostion. These findings are probably a result of (1) the high initial fertility levels of the soils and (2) the fact that P, K and pH stratification was probably not significant during the first year of no-till production. In the corn study, the higher N rate significantly increased com 71 72 grain and stover yields in both the conventional and the no-till plots. Nutrient analysis and visual deficiency observations support the findings of others showing that at subOptimal N levels, N uptake is less in no-till than in conventional tillage systems. Previous research has suggested that decreased N efficiency in no-till may be due to an increased potential for leaching, immobilization, denitrification and volatilization and less mineralization of N in no-till systems as compared to conventional tillage systems. Corsoy 79 significantly outyielded SRF-200. As the use of minimum tillage practices increases variety trials under no-till conditions will become more important. Early season vigor and disease resistance are two characteristics that corn and soybean varieties will need to be well-suited to use with no-till. The effect of the surface mulch on soil moisture and soil temperature was small in these irrigated studies. Bulk density was significantly higher and air-filled porosity was significantly less in no-till plots compared to conventional plots, but these differences did not appear to affect corn yield, nutrient composition or root length density. As these tillage studies become more established, the differences in soil physical and chemical properties between the conventional and no-till plots are likely to become more evident. These differences may become great enough to affect root growth, nutrient availability and Yield 0 Recommendations I. The corn and soybean tillage studies established in East Lansing in 1982 are pr0posed to continue for a ten year period to allow? for a thorough evaluation of the treatments. Several changes in the management practices may make the results from these studies more applicable to farm situations. A) Ammonium nitrate should be discontinued as the main N fertilizer broadcast in these studies since it is an expensive and little used source in Michigan. Injecting anhydrous ammonia should be considered as an alternative. B) Hand weeding should be eliminated because mechanical weed control is not practical in no-till crop production and because hoeing leads to incorporation of surface applied nutrients. C) The benefits of irrigation on soybean yields and nutrient uptake in this study need to be evaluated. D) Plowing in the Fall instead of the Spring could improve seedbed conditions at planting. II. Soil chemical and physical properties should be evaluated several times over the duration of the project. A) Soil testing of samples taken at several depth increments (including.a shallow surface sample) is needed to monitor the movement of surface applied P and K and to determine the rate of surface acidification due to the surface application of N. B) Undisturbed soil cores for bulk density and air-filled porosity measurements should be taken at several depths in each tillage 73 74 system in order to determine the extent of the soil compaction in the two tillage systems. III. Research indicates that there are many alternatives to consider when develOping a nitrogen management program for no-till corn. In addition to rate, source and placement studies, research is needed to study the use of split application techniques, the timing of N fertilization and the use of nitrification and urease inhibitors. APPENDIX A PLANT AND GRAIN ANALYSIS FOR INDIVIDUAL TREATMENTS APPENDIX 75 Table 1a. Corn tillage study treatments. Treatment Tillage P-Placement1 N-Rate K—Rate ‘ kg N/ha kg K20/ha 1 Conventional Broadcast 168 56 2 Conventional Broadcast 168 168 3 Conventional Broadcast 336 56 4 Conventional Broadcast 336 168 5 Conventional Banded 168 56 6 Conventional Banded 168 168 7 Conventional Banded 336 56 8 Conventional Banded 336 168 9 No-till Broadcast 168 56 10 No-till Broadcast 168 168 ll No-till Broadcast 336 56 12 No-till Broadcast 336 168 13 No-till Banded 168 56 14 No-till Banded 168 168 15 No—till Banded 336 56 16 No-till Banded 336 168 1Phosphorus rate = 56 kg P205/ha. 76 OON.H NH NN ONN NO NN. OO. NN.N NO. NH.O OH OON.H NH NN ONN NN NO. NN. NO.N NO. ON.O NH OON.H NH NN OON NN ON. NO. NN.N NO. O0.0 OH ONH.H NH NN OON ON NO. NN. No.O NO. N0.0 NH ONH.H OH NN ONN NN NN. NO. ON.N NO. ON.O NH ONO.H NH NN ONN HN HO. ON. NN.N OO. NN.O HH ONN.H NH NN ONN NN OO. NN. NN.N OO. ON.O OH ONN.H NH NN OHN ON NO. ON. ON.O NO. NN.O N ONO.N HH NN OHN.H NHH NN. NN. N0.0 OO. H0.0 N ONH.N NH NO OHO.H OOH NN. ON. OH.O HO. OH.O N ONO.N NH Hm OON.H NN NN. NN. OH.O NO. NH.O O ONN.H NH OO OOO.H NHH NN. HN. NN.N OO. NN.N N ONN.N NH NO ONN.H HNH NN. ON. H0.0 NN. OH.O O ONH.N OH NO OON.H OHH NN. ON. ON.N OO. N0.0 N ONN.N HH NO ONO.H NNH NN. ON. NN.N NN. OO.N N ONO.N NH NO ONN.H NNH NN. ON. NN.N ON. ON.N H Sam I IN I HO OO ON ON Oz N: OO O O z HONOOONNN uamson .ucwswomHa msuonamona cam :ONumNNHHuumw anammmuoa cam amwouuHc .conuoe mmeHHu an Omuoowmm mm AHHOSB NHummv muamHa auoo mo cowuHmomEoo HmHameHm .mN OHQNH 77 0O NH mm NmN NO ON. NO. NO.N Om. HH.N OH NH NH ON OHN 0O NN. Ow. NO.N NN. HH.m mH Nm NH Om OON mm NN. Hm. NO.N mm. oo.m OH mm NH mm NON Nm NN. Hm. mm.N mm. Oo.m NH ON NH mm HNN HO ON. mm. NO.N mm. ON.N NH Om NH ON wNN OO NN. NO. OO.N mm. NN.N HH OO NH mm NON Nm NN. Nm. Om.N Om. Ho.m 0H ON NH ON OHN mm on. ow. NO.N mm. Oo.m N HO NH HO OON OO NN. ON. NO.N mm. ON.N w NN NH NO HNN NO NN. NN. ON.N Nm. NO.N N mO mH NO OON OO NN. oN. NN.N NN. oo.m O mm NH mm ONN 0O NN. NN. NO.N NN. OH.N O NO NH Om NNN NO ON. ON. ON.N mm. ON.N O NO NH NO OmN Hm NN. Hm. NO.N mm. NN.N M NO OH OO NON OO NN. ON. NO.N Om. ON.N N NO NH NO NON GO ON. NN. NO.N Om. OH.N H San N HO 8 ON ON O: NO OO O O z HOOEONOO. unwaon .ucmamomHa monogamosa cam coHumNHHHuumm aaHmmmuoa Ocm :mwouuH: .Oonuoa ommHHHu NO Omuommmm mm mmmH umo cuoo mo OOHuHmoaaoo HmuamamHm .mm oHOmH 78 NN H.O NN NN 0.0 HN. NO. NN. NO.H OH NN O.N NN NN N.N ON. NO. NN. NO.H NH OO O.N ON HN 0.0 NN. ON. NN. NN.H OH NO N.N NN HN N.N NN. ON. NN. ON.H NH NN O.N ON NN O.NN NH. NO. NN. OO.H NH NN H.N NN ON H.N NN. NO. NN. OO.H HH NO N.N ON ON N.N NN. ON. NN. ON.H OH NN O.N NN ON N.N NH. NO. NN. NN.H N NO O.N NN NN 0.0 HN. NO. NN. OO.H N NO N.N ON NN 0.0 NN. NN. NN. NO.H N ON H.O NN OO O.N HN. HN. NN. HO.H O NO N.H HN ON N.O HN. ON. NN. OO.H N ON N.N NN NN N.N ON. ON. NN. NO.H O HO O.N ON ON N.O ON. ON. NN. NO.H N ON N.N NN NN H.N NH. OO. NN. OO.H N NN O.N ON NN N.O HN. NO. NN. HO.H H 1 San N I H< :0 :N mm a: N: M m z ucmaummue ucmamHm .ucmamomHa msuonmmosa Ocm =0HumNHHHuuwm EsHmmmuoN Ocm cmwouuHc .Oonuwa wNmHHHu NO Omuuwmwm mm :Hmuw auoo mo :OHuHmoaaou HNuamEmHm .mO meme 79 NNH N.O OH HON ON NN. NO. NN.H NNO. ON. OH NNN O.N NH ONN NN NN. NO. ON.H NOH. NN. NH ONH O.N NH NON NH ON. NN. NN.H NNO. NO. OH OON N.O OH NOO NN ON. NN. ON.H NOH. OO. NH NOH 0.0 OH NNN NN ON. HO. NN.H NNO. NN. NH HOH N.O OH NNN NN NN. NO. HN.H OOH. ON. HH NOH H.O NH NON ON NN. NN. NO.H NNO. OO. OH NON N.N OH NNN NN NN. NN. NN.H OOH. NO. N HNH H.N ON HON NN NN. NO. NN.H ONO. ON. N NOH N.O HN NNN NN ON. NO. NN.H NNO. NN. N NNH N.N NH HNN ON NN. ON. HN.H NNO. ON. O NOH N.O NH NNN HN NN. OO. OO.H ONO. HN. N NNH N.O HN NON NN NN. NN. OO.N NNO. HN. O OOH N.O OH NON NN HN. HO. HO.H ONO. HN. N NOH N.O OH NNN ON NN. NN. NN.H ONO. HN. N NNH N.N OH NNN NH NN. NN. OO.H NNO. ON. H Ema IN HO so :N wm a: Nz mu x m z unwaummuh unmEmHm .uamamUMHN mSHOONmOON Ocm cOHumuHHHuumm BaHmmMuon Oaw cmNouuH: .OOOumE mNmHHHu NO Omuomwwm mm um>0um cuou mo =0HuHmoaaoo HmucmEmHm .MN mHOmH 80 Table 6a. Soybean tillage study treatments. Treatment Tillage Variety P-Placement1 K-Rate kg KZO/ha 1 Conventional Corsoy 79 Broadcast 0 2 Conventional Corsoy 79 Broadcast 56 3 Conventional Corsoy 79 Banded O 4 Conventional Corsoy 79 Banded 56 5 Conventional SRF-ZOO Broadcast 0 6 Conventional SRF—ZOO Broadcast 56 7 Conventional SRF-ZOO Banded 0 8 Conventional SRF-ZOO Banded 56 9 No-till Corsoy 79 Broadcast 0 10 No-till Corsoy 79 Broadcast 56 ll No-till Corsoy 79 Banded O 12 No-till Corsoy 79 Banded 56 13 No-till SRF-ZOO Broadcast O 14 No-till SRF—ZOO Broadcast 56 15 No-till SRF-ZOO Banded 0 16 No-till SRF-ZOO Banded 56 lPhosphorus rate = 56 kg P205/ha. 81 NOH OH OO ONN NN NN. ON.H NN.N OO. HN.N OH NO NH NO NNH HO ON. OH.H NN.N NO. NN.N NH NN OH NO NNH NN NN. NN.H NN.N NO. NN.N OH NN OH NO HNH ON NN. NN.H NN.N NO. NH.N NH ON NH OO ONH OO HN. NO.H NN.N NO. ON.N NH OO NH NO NNH NO NN. HO.H HN.N NO. ON.N HH NN NH NN NNH NN ON. NN.H NO.N NO. ON.N OH NN NH NO NNH NN HO. HN.H NN.N ON. NN.N N NNH NH ON ONH ON HN. NH.H HN.N NO. HH.N N NN NH NN NOH ON NO. OH.H NN.N OO. ON.O N NN OH NN ONH NN NN. ON.H NN.N NO. NN.N O NN HH NN ONH HO NN. ON.H ON.N OO. ON.O N OHH NH ON OON HN ON. NH.H NN.N OO. HH.N O NOH NH NO NON OO NN. NH.H NN.N ON. NN.N N ON NH NN NNH NO ON. ON.H NN.N NO. NH.N N NN OH ON NNH ON NN. NN.H NH.N NO. NH.N H llllll IIIIIIIIIIIIIEON IN 3 no 5 mm a: w: 8 o. m z ”.55 8:. ucwEon .cOHumNHHHuumw aaHmmMuoa Oam ucmawUMHa mSHOOOmoOn .NumHum> .OOOumE wNmHHHu NO Omuommwm mm AEoOHO NHumwv mucmHO cmmONom mo aoHuHmoaaoo kuawEon .mN mHOmH 82 HH OH NO ON ON ON. HH. OO.N NN. OH.O OH NH NH ON NN HN OH. OH. OO.H OO. HN.O NH OH OH ON OO HN OH. HH. NO.H NN. N0.0 OH HH OH NO ON NN OH. OH. OO.H NN. O0.0 OH HH OH HO OO NN OH. OH. NO.H ON. OH.O NH ON OH HO NOH NN OH. OH. OO.H ON. NN.O HH NH NH NO NO HN NH. OH. NO.H NN. ON.O OH OH NH ON ON HN NH. HH. NO.H NN. O0.0 O O OH OO ON HN HN. HH. OO.H ON. ON.O O ON OH HO OO NN OH. HH. OO.H NN. NN.O N Om NH OO OO NN OH. HH. HO.H NN. ON.O O NH NH NO ON ON OH. NH. NO.H NN. O0.0 N HH NH ON ON ON OH. NH. HO.H HN. NH.O O ON NH ON OO HN OH. HH. OO.H NN. ON.O N NN OH HO NO HN NH. HH. NO.H ON. O0.0 N NO OH OO OO HN OH. HH. OO.N NN. NN.O H San N H< so ON on a: O: OO O O z ucmaummua UGQEUHM .coHumNHHHuuoN asHmmmuoO cam ucmamomHO msuoOamoOa .NumHum> .OoOumE mNmHHNu NO Omuomwwm mm comm ammONom No aoHuwwomEoo HmuamamHm .OO mHOmO BIBLIOGRAPHY l. 5. 9. 10. ll. 83 BIBLIOGRAPHY Alvey et. a1. 1980. Genstat: a general statistical program. Lawes Agricultural Trust. Rothamsted, England. Anon. 1978. Glossary of soil science terms. Soil Science Society of America. Madison, Wisc. pp 36. Anon. 1982. The history of no-tillage: Modern man comes a full circle. Ag. Chem. Age. 26(4): 10,38. Anon. 1982. Michigan conservation tillage survey. 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